Means for regulating the speed of photographic shutters.



' W. HUNT & W. TAYLOR.

MEANS FOR REGULATING THE SPEED OF PHOTOGRAPHIG SHUTTERS.

APPLICATION FILED NOV. 28, 1910.

Patented Nov. 21, 1911.

. F/GJ.

//VVEN TOIYS W. HUNT & W. TAYLOR. MEANS FOR REGULATING 'THE SPEED OFPHOTOGRAPHIC SHUTTERS.

APPLICATION TILED NOV. ?8 1910. 1,009,521, Patented N0v.21,1911

4 SHEETSSHEET 2.

FIG. 5.

rW/T'NEJ'SEJ MlhdMwg W7 mm m.

W. HUNT & W. TAYLOR.

MEANS FOR REGULATING THE SPEED OF PHOTOGRAPHIG SHUTTERS.

APPLICATION FILED NOV. 28. 1910.

Patented Nov. 21; 1911.

4 SHEETS-SHEET 3.

F/G. 0T

W. HUNT & W. TAYLOR.

MEANS FOR REGULATING THE SPEED OF PHOTOGRAPHIG SHUTTERS.

APPLICATION FILED NOV. 28, 1910 1,009,521. Patented N0v.21, 1911.

4 $HEETS-SHEET 4.

UNITED STATES PATENT OFFICE.

WILFRED HUNT, OF GLASGOW, SCOTLAND, AND WILLIAM TAYLOR, 0F LEICESTER,

ENGLAND.

MEANS FOR REGULATING THE SPEED OF PHOTOGRAPHIC SHUTTE RS.

Specification of Letters Patent.

Patented Nov, 21, 1911.

Application filed November 28, 1910. Serial No. 594,554.

To all whom it may concern:

Be it known that we, VVILFRED HUNT and WILLIAM TAYLOR, subjects of theKing of Great Britain and Ireland, and residents, respectively, ofGlasgow, Scotland, and Leicester, England, have invented certain new anduseful Means for Regulating the Speed of Photographic Shutters, and ofwhich the following is the specification.

The invention has for its object to provide means for regulating thespeed of photographic shutters, such that, while a wide range ofexposures may be provided, the regulation is not subject to variation bythose various factors which disturb the regularity of controling deviceshitherto employed.

Essentially the invention consists in applying to a moving part of theshutter and to control its period a rotatory mass rotated first in onedirection and then in the other after the manner of a clock balancewheel. Means are provided for rotating this mass with reversal a seriesof amounts different for the different exposures it is desired theshutter should givefrom zero (no) movement for the maximum speed of theshutter to a maximum for the minimum speed. thereof.

Where the shutter is of that now wellknown type opening rapidly andclosing rapidly and in which the parts are held for the duration ofexposure in the open position by a detent or the like released to closethe shutter at the termination of the exposure, the balance wheel may beoperated by the impact of a tappet operated with or by the openingshutter and engaging a coacting tappeton the wheel. A spring buffer isplaced to receive the wheel upon its performing a prescribed travel andreacts to return it, means being provided and operated by it on itsreturn to release the detent retaining the shutter open whereupon thelatter closes. Variability of the amount of movement of the wheel and soof the period is attained by varying the position of the buffer. Such aform of device is obviously applicable to any form of shutter held oradapted to be held by a detent in open position during the period of anautomatic exposure.

Where the shutter is of that type in which there is no determinateholding open of the parts at mid exposurethat posure takes place duringa more or constant movement of the partsthere is applied a modificationof the device (also applicable to the first type of shutter) in whichthe balance wheel is rotated with re versal by suitable gearing such asa toothed quadrant engaging a pinion on the balance wheel spindle. Thetoothed quadrant is re ciprocated by link or like motion from a movingpart of the shutter, and through the resistance of the balance wheelcontrols directly the speed of movement of that part and so the durationof the exposure given by the shutter. The amount of reciprocation giventhe quadrant is varied by means of any convenient form of link orvariablestroke device interposed between it and the part from which itreceives its motion.

In order that the invention and the manner of performing the same may beproperly understood there are hereunto appended four sheets ofexplanatory drawings showing in Figs. 1 and 2, Sheet 1, in brokensectional plan on the'line aa, Fig. 2, and in broken sectional elevationon the line bb, Fig.' 1, respectively an example of a device in whichthe balance wheel is impact-operated, in Figs. 3 and 4, Sheet 2, in planand in broken sectional elevation on the line c-c, Fig. 3, respectivelya second example in which the balance-wheel is impact-operated, in Figs.5 and 6, Sheet 3, in like views (the latter on line (za, Fig. 5) anexample of the application of an impact-operated balance wheel to thecontrol of a shutter described in the specification of Taylors UnitedStates patent application of 25th April, 1904, in Figs. 7 and 8, Sheet4, in like views an example in which the balance wheel is directlyconnected by gearing to and operated by the shutter, and in Fig. 9 inplan a variation upon this form.

It is here to be pointed out that with the exception of that shown asapplied to the shutter which is the subject-matter of the patenthereinbe'fore referred to the examples are of necessity diagrammaticthedevice is obviously applicable in one or other of its forms to anyshutter operating near the lens and in the multiplicity of knownshutters it is not possible to showhere the exact is, in which exmeansor manner of application in any particular case, butt-his is a matter ofselection and minor design within the scope of those skilled.

The drawings are to a large scale.

In the diagrammatic and illustrative example shown in Figs. 1 and 2 ofthe first modification hereinbefore referred to, the impact-operatedbalance wheel 2 (indicated by chain lines in'Fig. '1 which is asectional plan beneath its level) has upon its under side a radialtappet 3. This tappet 3 is engaged by an upstanding pin 4 assumed forthe purpose of illustration to be moved from the left hand dot-tedposition during opening of the ShuttBFtO the right hand dottedposition,remaining there while the shutter is open and finally during closing ofthe shutter returning to the left hand position. Thetappet 3 is alsoadapted to engage the upstanding end 5 of a buffer spring 60f hair-pinshape bent to give resiliency in its upper part, threaded through aplate 7 so that it may oscillate therein and having its under end 8 bentdown at right angles coincident with the end 5 and engaging a volutegroove 9 in a base plate 10 on which is a stud 11 in which the spindle12 of the balance wheel 2 is pivoted, while its upper end is supportedby a bridge13. The plate 7 is engaged between the head of the stud l1and the base plate 10, a washer being interposed. Thus the plate 7 isrotatable about the axis of the balance wheel and a handle 14 bent downand passing out through a slot 15 is provided for its rotation. A stop16 in the base plate 10 is provided engaging the tappet 3, while a lightwatch hair-spring 17 fixed between the balance wheel and the bridgetends always to keep the tappet against this stop. A detent lever 18pivoted on a stud 19, controlled by a spring 20 co-acting with a stop21, having in it a jaw 22 to engage the pin 4 and an inclined surface 23engaged by the returning tappet 3, is shown as illustrative of theaction.

In operation, upon release of the shutter for exposure the pin 4commences to travel to the right and bearingupon the detent lever 18presses it out of its way. The pin 4 moving with speed encounters thetappet 3 andby impact drives the balance wheel 2 around againstthe lightresistance of the spring 17 (the balance wheel being suitablyproportioned to the force exerted upon it by the pin 4). The balancewheel 2 then proceeds until its tappet 3 encounters the upstanding end 5of the buffer spring 6. and in the meantime the pin 4 entersand is heldin the jaw 22' of the detent lever 18. Upon its tappet 3 encounteringthe buffer spring end 5 the wheel is brought to rest and thenaccelerated in the opposite and return direction by that spring. Uponthe return of the balance wheel, its tappet 3 engages the surface 23 ofthe lever 18 and passing over that surface frees the pin 4 from the jaw22, the pin 4 returns to the left and the shutter closes. The time thepin 4 remains held by the jaw 22, and consequently the time for whichthe shutter remains open, depends upon the distance traveled by thebalance wheel and by the resistance period of the buffer spring 6(modified in a negligible degree by the spring 17). The distance thewheel runs depends upon the position of the buffer spring 6. Itsposition is angularly adjustable by rotation of the plate 7 by thehandle 14. The resistance period of the buffer spring 6 depends upon theradial position of its end 5. In the position shown in Fig. 1 the travelof the wheel is the greatest, the radial distance of the end 5 theleast; so that not only does the wheel take the greatest time toencounter the buffer spring but that spring also takes the greatest timeto reverse the wheels motion. As the handle 14 is movedaround clockwise,not only is the angular travel of the wheel reduced, but the bufferspring end 5 being moved radially out by the engagement of itscoincident end 8 with the volute groove 9, its resistance relatively tothe wheel is increased and the total period of the wheel reduced. Thus a95 wvide range of periods is obtainable between the positions of thespring 6 for least angular movement of the wheel and for greatest. Ashereinafter shown in one example, the radial movement of the bufferspring 6 may be dispensed with as suiiicient variation of speed isobtainable by variation of angular position alone.

In the illustrative example shown in Figs. 3 and 4 the balance wheel 2,preferably controlled by a light hair spring (omitted for the sake ofclearness), is recessed upon its upper surface in the form of a voluteinternal ratchet having a series of teeth 24, 25, 26, 27, 28, 29, and astop 30. The buffer spring 6 arranged substantially radially has adown-turned end 5 adapted to engage these teeth and is anchored upon aslide 31 which may be moved radially in guides 32 by an eccentric pin 33engaging a slot 34 in it and carried on a disk 35 adjustable by hand.The same effect is thus obtained as in the foregoing examplethe annularmovement of the balance wheel and the radial position of the bufferspring are jointly adjusted by setting the disk 35. In this example itis assumed that the pin 4 or other part moving with or moved by theshutter in opening and closing instead of reciprocating moves in 'astraight line with a stoppage in the middle of its travel and while theshutter is open. The two devices illustrative of this are of courseinterchangeable. and moreover they form no direct part of the invention,nor are they limitative.

skilled and without invention than it would be possible even tocatalogue here. The pin 4 in this example passes from left to right, asindicated by dotting, and in so passing engages a pawl 36 pivoted on thebalance wheel 2 controlled by a spring 71 and acting against a stop37-this pawl being movable only so that the pin 4 may lift it inreturning from right to left when the shutter is being set. The stop 30acts against the end of the spring 6 to hold the wheel in the positionshown. Upon the pin 4 engaging with impact the pawl 36, the balancewheel is thrown around as before while the pin enters and is held in ajaw 38 in a detent lever 39 similar to the detent lever 18, the shutterbeing now open. On its return the pawl 36 encounters a slope 40 fixed onthe end of the lever 39 and above the level of the pin 4 and moving thatlever release-s the pin 4 which moves to the right hand position, theshutter meanwhile closing.

In Figs. 5 and 6 the device as applied to a shutter of the typedescribed in the specification of the prior patent hereinbefore referred to only differs in structural detail from that first hereindescribed in that the butter spring 6 is moved angularly only and notconjointly radially. This'spring is anchored around the edge of a plate7 rotatable about the balance wheel pivot 12 and bearing a pinion 41with which there gears a pinion 42 operated by a handwheel 43 outsidethe case 44 of the-shutter and by which the angular position of thespring may be adjusted. The tappet 3 is in the form of a simple radialpin, engages the upturned end 5 of the buffer spring 6 and is engaged bythe impact device. The impact device consists simply of a tail-piece 45on what is termed the controlling gate 46 of this shutter. As will beseen in Fig. 6, which is a sectional elevation to an'enlarged scale onthe line aa of Fig. 5, the end of this tail piece 45 is formed with aninclined surface 47 and a part 48 acting as a stop. Opening of theshutter raises the tail piece. its incline 47 flies up against the pin 3and operates the wheel 2. Upon the wheel returning the pin 3 engages theincline -47 forces the gate down and releases the shutter to close.

Figs. 7 and 8 illustrate in diagram an example of the secondmodification. These illustrations and also Fig. 9 being arranged for thesake of clearness are obviously not applicable directly to commercialshutters, but their modification to suit these is only a matter ofrearrangement of their parts. In this example the spindle 12 of thebalance wheel 2 has on it a pinion 49 which gears with a quadrant 50 ona fixed pivot 51. On the quadrant 50 is an arm 52 hearing, on a pin 72,a block 53 engaging a link 54 of channel-wctionJ One end of the link 54is attached to a lever 55 on a fixed center 56 and capable of rotationthereon through an arc of teeth 57 and a pinion 58. The other end of thelink 54 is reciprocated in any suitable way from the shutter, forinstance it may be connected by a link 59 to a pin 60 on a part 61 ofthe shutter which is assumed to rotate once during exposure. The amountof motion transferred from the link '54 to the quadrant 50 and so to thebalance wheel 2 depends of course upon the position of that linkrelatively to the block 53. 7 Thus, the control offered by the balancewheel may be varied from zerowhen the link 54 is in such a position thatno motion is transmitted to the wheelto maximumwhen it is in positionfor the transmission of maximum motion. The alteration in position iseffected by moving the lever 55 by means of the pinion 58.

In the example shown in Fig. 9 the balance wheel 2 with its pinion 49and the quadrant 50 with its block-bearing arm 52 are carried in a frameformed of straps 66 held by distance thimbles 67 and pivot-ed on a fixedpivot 62 about which the whole is turnable by an arc of teeth 63 formedon one of the straps 66 and'engaged by a pinion 64. The channel link 54is on a fixed pivot 65 at one end, and at the other end is connected tothe shutter so as to be reciprocated thereby by the link 59. Movement ofthe frame 66 obviously varies the movement transmitted from the link 59as the block 53 is moved to or from the pivot 65.

. The essence of the invention is the provision of a balance wheelrotated with reversal, interconnecting means between it and the shutterfor the control of the latter, and means for varying the amount ofrotation of the wheel. The essence gener ically of the first form isthat the balance wheel is free, rotates underthe impact of a movingshutter part, and returns to release a detent holding the shutter open.The generic essence of the second form is that the balance wheel isoperated by interconnected gearing and directly controls the wholemovement of the shutter. It is apparent that the balance wheel in thefirst form need not receive direct impactit may receive impact throughgearing of the kind applied in the second form.

Since the period of exposure is determined by the inertia of a mass andthe power of springsfactors practically speaking invariableit followsthat the control offered by the device is much more consistentlyaccurate than is possible with other devices such as brakes or pneumaticdashpots hitherto applied.

What we claim is 1. A controlling device for photographic shutterscomprising a balance wheel operatively connected to the shutter tocontrol its exposing period, means for rotating the balance wheel withreversal during the exposing period of the shutter and means for varyingthe amount of rotation of the balance wheel.

2. A controlling device for photographic shutters comprising a balancewheel, an impact device on the shutter encountering the balance wheel torotate it, a buiier device encountered by the balance wheel to return itand adjustable in position circumferentially to the balance wheel, and adetent holding the shutter and operated by the returning balance wheel.

3. A controlling device for photographic shutters comprising a balancewheel, an impact device on the shutter encountering the balance wheel torotate it, a butler device encountered by the balance wheel to return itand adjustable in position circumferentially and radially to the balancewheel, and a detent holding the shutter and operated by the returningbalance wheel.

4. A controlling device for photographic shutters comprising a balancewheel, an impact device on the shutter encountering the balance wheel torotate it, a buffer device encountered by the balance wheel to return itand adjustable in position circumferentially to the balance wheel, adetent holding the shutter and operated by the returning balance wheel,and a spring tending to return the balance wheel to normal position.

5. A controlling device for photographic shutters, comprising a balancewheel operatively connected to the shutter to control its exposingperiod and means engaged by the shutter to rotate said balance wheelupon the opening of the shutter, substantially as described.

6. A controlling device for photographic shutters, comprising a' balancewheel and means engaged by the shutter to rotate said I balance wheelupon the opening of the shutter, in combination with a detent forholding the shutter open and means in connection with said balance wheelfor freeing said detent after a predetermined open period for theshutter.

7 A controlling device for photographic shutters, comprismr a balancewheel and means engaged by the shutter to rotate said balance wheel uponthe opening of the shutter, in combination with a detent for holding theshutter open and means in connection with said balance wheel for freeingsaid detent after a predetermined open period for the shutter, togetherwithmeans for varying the rotation of said balance wheel to vary thetime within which said detent is freed thereby.

8. A controlling device for photographic shutters, comprising aspring-actuated controlling member, means operativel engaged by theshutter for moving said member against the action of its spring and anoperative connection between said member and the shutter for controllingthe exposure period of the latter.

9. A controlling device for photographic shutters, comprising aspring-actuated controlling member, means operatively engaged by theshutter for moving said member against the action of its spring and anop erative connection between said member and the shutter forcontrolling the exposure period of the latter, together with means forvarying the intensity of the action of the spring for said controllingmember.

In testimony whereof we have signed our names to this specification, inthe presence of two subscribing witnesses.

WILFRED HUNT. WILLIAM TAYLOR.

Witnesses as to the signature of Wilfred Hunt:

DAVID FERGUSON, BARBARA MILLAR. Witnesses as to the signature of WilliamTaylor:

ARTHUR PIERCE, H. P. HAGON.

